Playback to Yamaha RX-V677 with BubbleUPnP fails

[bilditup1]

This happens every time I try to play a file to my receiver using BubbleUPnP for Android as a control point:

07-17 16:37:04 [Fatal Error] :4:38: The value of attribute "val" associated with an element type "NextAVTransportURIMetaData" must not contain the '<' character.

An 'Unable to play' message pops up on the receiver, an 'Action Timeout' message pops up on BubbleUPnP on my phone, and nothing plays back.This happens whether or not I also use BubbleUPnP as a proxy - in other words, from UMS's perspective, the BubbleUPnP Server instance on the same PC is the renderer - or not. My receiver is a Yamaha RX-V677. All software and firmware, including UMS, are the latest available versions. Trace logs attached. Hopefully someone can make something of this, and thanks for your time.